| At present, Soil alkalization has become a worldwide problem, the proportion of saline soil area is up to10%of the world’s total land area, thus making the problem more serious. Soil alkalization has seriously affected agricultural production, which has been critical to the stability of global ecosystems and biological diversity. However, with the increasing number of population and decline of arable land, mankind has faced the shortage of food and resources, and how to solve this problem, Besides improving grain yield, the only way is to develop the use of saline land. Currently the measures of salt-alkali soil improvement are mainly engineering, chemical, physical and biological measures, in which biological measures are more practical and scientific, and using salinity of soil alkalization plants make improvements in a number of biological measures is the most ecological science. Thus, how to use saline land, desert land and salty water resources has become an urgent need to address global issues.[Belamcanda chinensis (L1) DC1] as iris plants, also known as butterfly flower, flat bamboo root, etc, is a perennial herb, and Its dried rhizome which is cold, bitter, have the detoxification, Liyan Phlegm, scattered knot swelling capabilities for phlegm dampness, sore throat, cough sputum, wheezing, chest stuffiness, milk desease, scrofulous tuberculosis, boils embolism treatment, which is expensive and short-supply medicine on the market timber, what is more B. chinensis has brightly colored flower, exotic flower plant type, and high ornamental value, which can be used as a new type of ground cover plants used to achieve the dual purpose of drug garden. Recently we have discovered that B. chinensis are more adaptable, resistance to drought, and cold, reduce soil alkalinity. It can play a role in soil and water conservation on sand-fixing, renovation construction waste land and so on, but we are unclear of he ability for B. chinensis in salt-alkali and salt-alkali stress and the response mechanism.Therefore,in light of the character of salt-alkalinized soil in northeastern China, this experiment with different salitines, different molar ratio, and pH were mixed by NaCl, Na2SO4, Na2CO3, NaHCO3, In the proportion of alkaline salts into ascending order six treatment groups, labeled CK and the control group A, B, C, D, E, and set of four concentrations within each group, followed0,40,80,120mmol/L, to simulate the different salinites and pH to inestigate the stress experiments on salt-alkali stress, By analyzing the different physiological and biochemical indicators in seedlings of B. chinensis on salt-alkali stress, such as:the response of chlorophyll content, penetration protection substances, metabolites it is easy to understand the mechanism of salt tolerance. And using the SNP, Spd, etc. which are exogenous substances of plants can induce salt resistance to as a research of salinity stress on B. chinensis seedling damage mitigation, which made the way to ease the hurt, understand eco-physiological adaptive mechanisms on B. chinensis and its salt-alkaline habitatto extensive cultivation of medicinal plants flowers development, improvement, use of saline land and provide scientific and theoretical basis. The main results of this study are as follows:1. Composition and molar ratio of salt to five different treatment compositions are from group A to group E with the increase in the proportion of alkaline salts pH value also showed a significant increase in the trend, In addition,within the same same treatment group, pH values with increasing total salt concentration was not significantly changed. The range of pH values is greater between groups than within a group, and there are interactions between salinity and alkalinity.While the role of the interaction of salinity and alkalinity B. chinensis Seedlings larger impact than both of them individually caused, And once again verify the effects of alkali stress on plants is mainly due to the impact of high pH, B. chinensis seedlings not only cope with osmotic stress, ion toxicity and other factors, but cope with high PH, which have to pay more matter and energy.2. The physiological response mechanism is very complex in seedlings of B. chinensis under salt-alkali stress. The different indices in seedlings of B. chinensis were inhibited reduced in different degrees under salt-alkali stress, such as (height, aboveground biomass, belowground biomass), but the shoot ratio was increased in seedlings of B. chinensis under different levels of salt-alkali stress, It is descript that salt-alkali stress inhibite the growth, development of B. chinensis seedlings, but in which high PH is the key factor limiting B. chinensis seedlings growth and development.3. The chlorophyll a, chlorophyll b and total chlorophyll content of B. chinensis leavestreated under salt-alkali stress were inhibited all increased at first and then decreased with the extended treatment days. The content of chlorophyll a has the trend of increasing in the early days, and then decreased in the middle and late days of treatment. TheContent of chlorophyll b and total chlorophyll were all increased in the early and middle days,and then decreased in the late days of treatment.Salt and salt concentration ratio of the content of both chlorophyll b and total chlorophyll were increased under different salt composition and molar ration, and different salt concentration. In addition, the chlorophyll content also increased when the Ph values of treatment up to ten or more. And the factor of time is different with the different of the salt ratio and salt concentration, and there is interaction between the alkali concentration and salt concentration. and the proportion of salt and salt in the three periods have significant interaction impact of the interaction between the chlorophyll content is far greater than its impact on them individually.But after exogenous substances SNP, Spd treatment, which can mprove the content of chlorophyll, and the SNP and the best material Spd two recovery recovery times are10d, in which we set several concentration gradient, the optimum concentration of SNP recovery is0.25mmol/L, Spd is0.1mmol/L.4.The production rate of the O2-and MDA content of seedlings of B. chinensis. under the salt stress will increase, and continue increasing with treatment time. Time interacts with salt ratio and salt concentration,and the have interaction between salt ratio and salt concentration is stronger.The production rate of the O2-and MDA content will decrease when the plant is disposed with SNP and Spd the plant, Especially when disposed at30d with salt concentration at0.5mmol/L, the content of O2-in all the plant was at minimum. When SNP has recovered and with the treatment time of20d and concentration of0.05mmol/L, the content of MDA will be lowered to the minimum,It indicate that the best concentration of Spd to the MDA was0.5mmol/L. It means the allogenic material can protect the plant from the saline-alkali stress.5.The SOD, POD, CAT in the seedlings show different change rule under salt-alkali stress, and reveal different condition in different period, the activity of antioxidase was complicated.The activity of this three enzymes become increasing after disposing with different salt ratio.The activity of POD and CAT reached the max in term C. Medium-low salt concentration increased the activity of this3enzymes, high salt concentration decreased their activity, when the salt concentration was80mmol/L, they reached the maximum, the activity of SOD increased in pre and middle period,but decreased in the late period, which maybe due to the high strength stress, SOD function declined.The activity of POD and CAT may reach the max in the late, while the activity of POD increased remarkable. It means the SNP can enhance the activity of SOD, POD, CAT efficiently by an antioxidant system, thus ease the damage of salt stress to the seedlings.6.The soluble protein and soluble sugar of the plant under salt-alkali tress were all increasing, the content of soluble protein increases with time, and the content of soluble sugar was after rising first down.They all increased under different salt ratio and salt concentration.When the time is30d, both the salt concentration at120mmol/L and group C can make he content of soluble protein reached the max. When it is20d, both the salt concentration at120mmol/L and group E, can make the content of soluble sugar reached the max. In the middle period,the salt ratio has interaction with the salt concentration efficiently. After recovery processing with SNP and Spd, the best condition of SNP to the soluble protein were30d and0.05mmol/L, Spd were30d and0.25mmol/L.The best condition of Spd to the soluble sugar were10d and0.05mmol/L, Spd were20d and0.5mmol/L.7.The organic acids accumulation under saline-alkali stress was different, five organic acids were all accumulated, but oxalic acid,malic acid,citric acid and succinic acid were mainly accumulated in seedling leaves, in root there were oxalic acid and succinic acid, the exogenetic Spd can increased the oxalic acid and malic acid in seedlings, and decreased the glacial acetic acid and citric acid in leaves, The interaction between salt ratio and salt concentration are strongly, and they have synergy effect on organic acid content in seedlings.8.Under salt-alkaline stress, B.chinensis seedlings carried by absorbing inorganic ions and their synthetic organic solutes (soluble sugars, soluble proteins, organic acids) to conduct the osmotic adjustment, and to make the defensive response. Soluble sugar is the most important osmotica, increasing its content ensures a variety of enzymes (SOD, POD, CAT) activity increasing,and repairs the damage of membrane, so that the content of photosynthetic pigments also increased, it also decreased the pH via(by) secreting organic acids,shifting H+,egulating ion flow and breathing to release CO2etc, maintained ion balance and pH stability in vivo, thereby increasing its salt-alkaline tolerance ability.Therefore, We speculate that the salt-alkali tolerance regulatory mechanism of B. chinensis seedlings is very complex and may involves a variety of basic pathways of metabolic(Krebs cycle, photosynthetic carbon fixation, anaerobic respiration, etc.).In summary, salt-alkali stress on B. chinensis seedling impact, whether it is increased with increasing concentrations of alkali or salt, when the pH value is above9.5or more, or after concentration reached100mmol/L, with the intensity stress of increased, the damage to the B. chinensis seedling became larger, and since there is interaction between the alkali concentration and salt concentration, that effects on seedling B. chinensis greater than the individual does. And.during the process of the treatment with exogenous substances B. chinensis seedlings under salt-alkali stress, though, optimal recovery of various indicators appear time are slightly different,but in the seedlings of Shegan experiment, the optimum concentration of selected and relieved B. chinensis seedlings subjected of salinity stress injuries are SNP (0.05mmol/L), Spd (0.5mmol/L). |
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